@Reception123 - The DNS setting are hosted at WordPress and set to:
so http://3point0.science/ points at the WordPress site. Could that cause a problem?
wiki.3point0.science is only pointed at mw-lb.miraheze.org as required (and not any other external websites).
https://wiki.3point0.science/wiki/Main_Page seems to work fine now, so if you're happy, I'm happy to close this ticket.
Thanks for your quick help on this.